Insulating A Garden Shed

Hey guys,

I have a garden shed I was wanting to convert into a man cave. It would have TV's, computers, and such. Currently it has no vents or anything and is about 12"x14. I was planning on just putting insulation in the walls and then putting plywood over it. Would I want to insulate the roof area too? Right now it gets about 110 degrees in the summer and freezing in the winter. Just kinda looking to eliminate that and get a more comfortable environment. Would it be beneficial to add vents too? Any help or advice would be appreciated.

Insulating A Garden Shed

The shed was already built when I bought the property. It seems like they made it pretty tight and boarded off the roof area pretty good so. I'm not quite sure how to do the baffling and such. Any other alternatives or idea on how to make it work? Got some pictures so you can get a general idea.